Process for the preparation of bicyclic ketones



U i ed States Patent ce PROCESS FOR THE PREPARATION OF .BICYCLIC KETONES No Drawing. Application November 23, 1954 Serial No. 470,797

12 Claims. (Cl. 260-590) The present invention relates to a process for the preparation of bicyclic ketones.

The preparation of oxygenated organic compounds by the oxidation of hydrocarbons with the aid of an oxygen-containing gasan exothermic reactionis a delicate synthesis because the reaction has to be limited and selective. This synthesis has been developedonly recently, particularly by the use of the liquid phase which makes possible a more rigorous control.

The reaction is a chain reaction yielding, as first isolatable products, hydroperoxides of the formula ROOH, wherein R stands for ahydrocarbon radical, the subsequent selective decomposition of which gives the desired oxygenated compounds, either directly or by way of complex reactions.

Since 1920, metallic salts have been employed as catalysts for the synthesis of fatty acids from parafiins. Other analogous processes, in particular those described in U. S. Patents Nos. 2,223,493 and 2,223,494, have made possible the production of saturated diacids and saturated monocyclic ketones, starting fromsaturated monocyclic hydrocarbons. These processes are, however, bound up with'the fundamental disadvantage of giving rise to the formation of intermediary peroxideseminently unstable substancesthe manipulation, concentration and isolation of which involve serious dangers of explosion.

The primary objects of the present invention are:

(1) To embody or develop a liquid phase oxidation reaction, with the aid of an oxygen-containing gas, which makes possible the industrial and economical manufacture of bicyclic ketones, the C=O function of which is in an a-position of an aromatic nucleus, bythe oxidation of hydrocarbons, the molecule of which comprises at least one aliphatic chain interconnecting two carbon atoms which are part of an aromatic nucleus (which definition includes more especially diphenyl-methane and its homologs, acenaphthene, 9-l0-dihydro-anthracene, tetrahydronaphthalene, etc.);

(2) To selectively destroy the hydroperoxides as soon as they are formed in order thus to avoid any dangerous accumulation thereof.

These objects, and others which will be manifest from the description which follows, are realized by the process of the present invention which makes possible the selective preparation of ketones by oxidation in the liquid phase of the aforedescribed hydrocarbons, while reducing the peroxide content to practically zero, thus eliminating all danger.

For the oxidation of the said hydrocarbons under the conditions of the present invention (which will be set forth in detail hereinafter), there is employed as oxidizing agent oxygen or an oxygen-containing gas.

It is important to assure intimate contact between the liquid phase and the gas, and for this purpose use I 2,859,247 Patented ov. 4,

may advantageously be made of an atomization device of any suitable and per se conventional construction.

It is advantageous to maintain the reaction temperature between C. and 200 C., either by cooling or by supplying the necessary amount of heat over and above that already furnished by the reaction itself. Too low a temperature favors accumulation of hydroperoxides; too high a temperature reduces the yield because of the formation of secondary-products.

For the group of hydrocarbons involved in the proc ess of the present invention, chain reaction initiators are useless.

Briefly stated, the process according to the invention is characterized by the simultaneous employment, for the said hydrocarbons, of oxidation catalysts and of acid solvents which serve not only to decrease the induction period and to increase the speed of the selective reaction for the formation of the corresponding ketones, but also to reduce the content of hydroperoxides to a negligible value.

The catalysts thus employed are cations of metals such as vanadium, chromium, manganese, copper, zinc, silver,

tin, antimony, lead, bismuth, iron, nickel and cobalt; these cations are formed upon the dissolution of the metals or of an oxide or salt (for example chloride, nitrate, sulfate, etc.) of the said metals or of a soap (for example acetate, propionate, palmitate, stearate, naphthenate, etc.) of such metals, in the aforementioned acid solvent. The concentration of catalysts relative to hydrocarbon can be reduced, according to this invention, down to very low values of the order of for example however, this figure is not at all intended to be lirnitative, since other concentrations may be employed.

The acid solvents which can be employed according to the invention are straight-chain or branched-chain monobasic organic acids, particularly lower alk anoic acids, preferably acetic acid, propionic acid and butyric acid.

It is preferred that the molar hydrocarbon solvent proportion of the hydrocarbon-solvent mixtures employed according to the invention be within the range V30 f0 20. employed.

Any suitable and per se conventional apparatus may be employed; this may for example take the form of a tall cylindrical receptacle provided at its base with an oxygen distributor, and with means for heating and means 7 for cooling the liquid. A thermocouple may advantageously be employed for observing the temperature.

Typical presently-preferred embodiments of the invention are set forth, by way of illustration, in the examples which follow. In such examples, the temperatures are set forth in degrees centigrade. Parts by weight" bear the same relation to parts by volume as do grams tov milliliters. Percentages are by weight.

Example 1 A mixture of 583 parts by weight of tetralin (tetrahydronaphthalene), 315 parts by weight of acetic acid,

and 0.2 part by weight of cobalt chloride, CoCl- (preliminarily dissolved in the acetic acid) is introduced intothe oxidation apparatus which may conveniently be of Other molar proportions may, however, be

o y n W ll mtain less than 1% of peroxide. By a single" distillation of the reaction liquid, there are recovered 287parts by weight of unreacted Tetralin and 245 parts by weight of d-tetr'alone:

The authenticity of the a-tetralone is confirmed inter alia by conversion thereof into the oxime and semi-carbazone and by its refractive index.

The oxygen-in this example as well as in those which follow.may also conveniently be supplied in the form of an oxygen-containing gas, such as air.

Example 2 A mixture of 398 parts by weight of Tetralin, 176 parts by Weight of acetic acid, and 0.2 part by weight of manganous acetate (previously dissolved in the acetic acid) is introduced into the reaction vessel, and oxidation carried out after-the manner described in Example 1 for a period of 65 minutes at a temperature of 110.

From the resultant oxidation mixture which contains less than 1% of peroxide, 155 parts by weight of unreacted Tetralin and 171- parts by volume of tetralone are recovered.

Example 3 A mixture of 398 parts by weight of Tetralin (3 mol.), 176 parts by weight of acetic acid and 0.2 part by weight of Ni(OH) (previously dissolved in the acetic acid) is introduced into-the reaction vessel and oxidation carried out after the manner described in Example 1 for a period of 75 minutes at a temperature of 125 C.

From the resultant oxidation mixture which contains less than 1% of peroxide, 175 parts by weight of unreacted Tetralin and 154 parts by weight of a-tetralone are recovered.

The authenticity of the a-tetralone is confirmed inter alia by conversion thereof into the oxime and semicarbazone.

Example 4 A mixture of 396 parts by weight of Tetralin, 222 parts by weight of propionic acid and 0.2 part by weight of CoCl (previously dissolved in the acetic acid) is intro duced into the reaction vessel and oxidation carried out after the manner described in Example 1 for a period of 65 minutes at a temperature of 100 C.

From the resultant oxidation mixture which contains less than 1% of peroxide, 159 parts by weight of unreacted Tetralin and 166 parts by weight of a-tetralone are recovered.

Themolar yield'of tetralone relative to the reacted Tetralin'is '63 Example 5 A mixture of 745 parts by weightof Tetralin, 703 parts by weight of butyric acid, and 0.4 part by weightof cobalt chlorid,' CoCl (previously dissolved in the butyric acid) is introduced into the reaction vessel, and oxidation carried out as described in Example 1 but with a reaction period of 50 minutes'a'nd a reaction temperature of 110.

The resultant mixture contains less than 1% of peroxide. After fractionation, 297 parts by weight of unreacted Tetralin'and 388 parts by weight of tetralone (which represents a 76% molar yield relative to the reacted Tetralin) are recovered.

Example 6 -A mixture of 175 parts by weight of indane, 88 parts by weight of acetic acid and 0.2 partby weight of CoCl (previously dissolved in the acetic acid) is introduced into the reaction-vessel-and oxidation is carried out after the manner described in Example 1,-for a period of .65 minutes at a temperature of 85 C.

The resultant mixture contains less than 1%. of peroxide, in addition to the unreacted indane and indanone After elimination of such acetic acid as may be present and distillation of the unreacted indane, indanone-1 is recovered.

The authenticity of indanone-1 is confirmed inter alia by conversion thereof into 2-4-dinitrophenylhydrazone and by its refractive index. The yield of indanone relative to the reacted indane is 69% 1 Example 7 There are recovered parts by weight of unreacted acenaphthene and 70 parts by weight of acenaphthenone. The authenticity of acenaphthenone is confirmed inter alia by conversion thereof into the oxime and the 2-4-dinitrophenylhydrazone.

Example 8 A mixture of 336 parts by weight of diphenylmethane,

118.5 parts by weight of acetic acid, and 0.2 part by weight of CoCl (preliminarily dissolved in the acetic acid) is introduced into the reaction vessel, and oxidation carried out as described in Example 1, except that a temperature'of is employed and the treating period is 'extended to 65 minutes. T heresultant mixture contains less than 0.8% of peroxide, in addition to unreacted diphenyl-' methane and benzophenone.

After elimination of such acetic acid as may be present; the benzophenone is separated by precipitation thereof in the form of its oxime, and the unreacted diphenyl methane is distilled ofi.

The yield of benzophenone relative to the reacted diphenylmethane is 60%.

In any of the foregoing examples the particularly employed acid solvent may just as well be replaced byanother monobasic organic acid solvent. Thus, where acetic acid is mentioned, it may be'replaced by propionic acid or butyric acid or the like, and vice versa.

In each of the foregoing examples, the particular oxidation catalyst therein employed may as well be replaced by equivalent quantities of other of the hereinbeforedescribed oxidation catalysts, such as for example the'cations of such metals as vanadium, chromium, manganese,- copper, zinc, silver, tin, antimony, lead, bismuth, iron,

nickel and cobalt.

The procedure set forth in the foregoing examples may be applied with like success to other hydrocarbons whichcorrespond to initially given definition, asfor example,

fluorene, dihydrophenanthrene, dibenzyl, 9-10-dihydroanthracene whereby there are obtained the corresponding bicyclic ketones i. pheny'lbenzylketone and anthrone respectively.

e. fluorenone, phenanthrone,

The acid solvent which is employed according to the present invention is not only a solvent for the oxidation catalyst but also for the hydrocarbon being oxidized. The oxidation catalysts are per se conventional, i. e. are known oxidation catalysts. However the combination catalyst-solvent has a specific chemical effect since it secures the selectivity of the reaction and therefore the solvent is not to be considered only for its physical properties.

Having thus disclosed the invention, what is claimed is:

l. A process for the production of bicyclic ketones wherein the function C=O is in an a-position of an aromatic nucleus, which comprises oxidizing, in the liquid phase with oxygen-containing gas, a binuclear hydrocarbon including an alkylene chain interconnecting two carbon atoms, each of which is part of an aromatic nucleus, at a temperature comprised between about 80 C. and about 200 C. in the presence of a lower alkanoic acid solvent and of an oxidation catalyst, said catalyst being formed by dissolving in the lower alkanoic acid solvent a member selected from the group consisting of a metal, a metal oxide, a metal salt, and a metal soap, whereby the said binuclear hydrocarbon is selectively oxidized to the desired bicyclic ketone and the formation of undesired byproducts is suppressed.

2. A process for the production of bicyclic ketones where the function C=O is in an a-position of an aromatic nucleus, which comprises oxidizing, in the liquid .phase with oxygen-containing gas, a binuclear hydrocarbon including an alkylene chain interconnecting two carbon atoms, each of which is part of a benzenic nucleus, at a temperature comprised between 80 C. and 200 C., in the presence of a lower alkanoic acid solvent and of an oxidation catalyst, said catalyst being formed by dissolving in the lower alkanoic acid solvent a member selected from the group consisting of a metal, a metal oxide, a metal salt, and a metal soap, whereby the said binuclear hydrocarbon is selectively oxidized to the desired bicyclic ketone and the formation of undesired byproducts is suppressed.

3. A process for the production of bicyclic ketones where the function C=O is in an u-position of an aromatic nucleus, which comprises oxidizing, in the liquid phase with oxygen-containing gas, a binuclear hydrocarbon including an alkylene chain of one to four carbon atoms interconnecting two carbon atoms, each of which is part of a benzenic nucleus, at a temperature comprised between 80 C., and 200 C., in the presence of a lower alkanoic acid solvent and of an oxidation catalyst said catalyst being formed by dissolving in the lower alkanoic acid solvent a member selected from the group consisting of a metal, a metal oxide, a metal salt, and a metal soap, whereby the said binuclear hydrocarbon is selectively oxidized to the desired bicyclic ketone and the formation of undesired byproducts is suppressed.

4. A process for the production of bicyclic ketones wherein the function C=O is in an a-posifion of an aromatic nucleus, which comprises oxidizing, in the liquid phase with oxygen-containing gas, a binuclear hydrocarbon including an alkylene chain of one to four carbon atoms interconnecting two carbon atoms, each of which is part of a benzenic nucleus, at a temperature comprised between about C. and about 200 C. in the presence of an oxidation catalyst and of an alkanoic acid solvent in a molar proportion of 1 to 20 relative to the hydrocarbon, said oxidation catalyst being formed by dissolving in the alkanoic acid solvent a member selected from the group consisting of a metal, a metal oxide, a metal salt, and a metal soap, whereby the said binuclear hydrocarbon is selectively oxidized to the desired bicyclic ketone and the formation of undesired byproducts is suppressed.

5. The process of producing tetralone which comprises dissolving Tetralin and cobalt chloride in acetic acid and bubbling an oxygen-containing gas through said solution at a temperature of from about 80 to 200 C.

6. The process of producing tetralone which comprises dissolving Tetralin and manganese acetate in acetic acid and bubbling an oxygen-containing gas through said solution at a temperature of from about 80 to 200 C.

7. The process of producing tetralone which comprises dissolving Tetralin and nickel hydroxide in acetic acid and bubbling in oxygen-containing gas through said solution at a temperature of from about 80 to 200 C.

8. The process of producing tetralone which comprises dissolving Tetralin and cobalt chloride in propionic acid and bubbling an oxygen-containing gas through said solution at a temperature of from about 80 C. to 200 C.

9. The process of producing tetralone which comprises dissolving Tetralin and cobalt chloride in butyric acid and bubbling an oxygen-containing gas through said solution at a temperature of from about 80 C. to 200 C.

10. The process of producing indanone which comprises dissolving indane and cobalt chloride in acetic acid and bubbling an oxygen-containing gas' through said solution at a temperature of from about 80 to 200 C.

11. The process of producing acenaphthenone which comprises dissolving acenaphthene and cobalt chloride in butyric acid and bubbling an oxygen-containing gas through said solution at a temperature of from about 80 to 200 C.

12. The process of producing benzophenone which comprises dissolving diphenylmethane and cobalt'chloride in acetic acid and bubbling an oxygen-containing gas through said solution at a temperature of from about 80 to 200 C.

Robertson et al.: J. Chem. Soc. (London), 1948, pp. 1578-1585. 

1. A PROCESS FOR THE PRODUCTION OF BICYCLIC KETONES WHEREIN THE FUNCTION C=O IS IN AN A-POSITION OF AN AROMATIC NUCLEUS, WHICH COMPRISES OXIDIZING, IN THE LIQUID PHASE WITH OXYGEN-CONTAINING GAS, A BINUCLEAR HYDROCARBON INCLUDING AN ALKYLENE CHAIN INTERCONNECTING TWO CARBON ATOMS, EACH OF WHICH IS PART OF AN AROMATIC NUCLEUS, AT A TEMPERATURE COMPRISED BETWEEN ABOUT 80* C. AND ABOUT 200*C. IN THE PRESENCE OF A LOWER ALKANOIC ACID SOLVENT AND OF AN OXIDATION CATALYST, SAID CATALYST BEING FORMED BY DISSOLVING IN THE LOWER ALKANOIC ACID SOLVENT A MEMBER SELECTED FROM THE GROUP CONSISTING OF A METAL, A METAL OXIDE, A METAL SALT, AND A METAL SOAP, WHEREBY THE SAID BINUCLEAR HYDROCARBON IS SELECTIVELY OXIDIZED TO THE DESIRED BICYCLIC KETONE AND THE FORMATION OF UNDESIRED BYPRODUCTS IS SUPPRESSED. 